Metal Nitride films, such as Niobium Nitride (NbNx wherein x is approximately 1) have been extensively utilized in various fields of technology. Traditionally these nitrides have been applied as hard and decorative coatings but during the past decade they have increasingly been used as diffusion barrier and adhesion/glue layers In microelectronic devices [Applied Surface Science 120 (1997) 199-212]. NbCl5 for instance has been examined as a niobium source for Atomic Layer Epitaxial growth of NbNx, but the process required Zn as a reducing agent [Applied Surface Science 82/83 (1994) 468-474]. NbNx films were also deposited by atomic layer deposition using NbCl5 and NH3. [Thin Solid Films 491 (2005) 235-241]. The chlorine content showed strong temperature dependence as the film deposited at 500° C. was almost chlorine free, while the chlorine content was 8 at. % when the deposition temperature was as low as 250° C. Id. The high melting point of NbCl5 also makes this precursor difficult to use in the vapor deposition process.
A need remains for developing liquid or low melting point (<50° C.), highly thermally stable, Niobium Nitride precursor molecules suitable for vapor phase film deposition with controlled thickness and composition at high temperature.